This invention relates to an improved captive ball and socket joint used to movably connect two machine elements in a universal manner. Various machine elements which can be connected by a ball and socket joint are links, levers and brackets. This invention was developed and will be described in connection with automotive link components, namely counterbalance links such as gas springs, the two ends of which are connected to and provide a linkage between two relatively movable components of an automobile, e.g., the trunk and trunk closure lid. The connection joints are sometimes ordinary pivotal joints but it is becoming more preferable to use ball and socket joints which permit a universally movable pivot connection between the two ends of a gas spring and the automotive elements when the link or gas spring is not mounted for movement in a plane perpendicular to the closure lid hinge center line, thereby necessitating an attachment with omni-directional capability. Components such as gas springs are usually furnished for installation with part of the end connections, usually an apertured lug or a socket, welded or prefastened to the ends of the gas spring. When the spring link is installed, the support part of the end connector is normally fastened to the automobile body or to a bracket on the trunk or hatch lid. When the spring link is installed with sockets to be mated with a ball, some form of clip or separate fastening device is then installed to hold the ball and socket together. It is desirable that the element, e.g., spring link, be preassembled with complete ball and socket end joints, the ball component being held captive in the socket component so they will not become separated when shipped, stored and handled. The worker then merely has to place the ball and stud component in the desired location on the automobile part and secure it in place.
Captive ball and socket joints have been proposed where the ball and the socket are both made from steel and the performance has been satisfactory. But it has become desirable to use a bearing material as apart of the ball and socket joint to avoid noise which can occur when steel moves against steel without lubrication which is often neglected in automotive gas spring end fittings. Such construction with bearing material in the socket has been proposed but the known constructions are not well adapted to mass production and machine controlled assembly.
Various examples of ball and socket joints are seen in the following U.S. patents: U.S. Pat. Nos. 1,759,430 to D. Benjamin and 1,989,116 to J. N. Strauss are examples of split socket bearing members enclosed in a housing and embracing a ball head of a ball unit, and in both patents a separate clip unit holds the bearing pieces in the housing; U.S. Pat. No. 2,855,655 to M. H. Aldredge shows a multi-piece ball and socket joint in which a multi-piece socket cup receives a plural part ball and a half round bearing part and the socket cup to spun over to retain the multi-piece joint as an assembly; U.S. Pat. No. 3,495,858 to G. Kindel shows a multi-layered socket insert, rubber pieces and a metal shell over a ball headed stud, all parts being held in a cup member in which the peripheral edge is swaged over a closure plate to hold all parts in assembly; and U.S. Pat. No. 4,577,989 to E. Ito shows a more sophisticated ball joint somewhat like the Kindel patent teaching. None of the foregoing prior patents teaches access through the socket housing to insert a drive tool to cooperate with a portion of the ball stud. That aspect is however, essentially taught by U.S. Pat. No. 4,768,895 to G. C. Ludwig et al although that patent does not teach the multi-part bearing socket unit within a shell housing. Further, none of the prior patents teaches the combination of a cup-shaped shell with apertured bottom wall enclosing a split socket bearing embracing a ball head of a ball stud and with the periphery of the housing welded or otherwise fixed to an apertured lug to render the ball stud captive within the socket and shell.